/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.state;



import com.bff.gaia.unified.sdk.annotations.Internal;

import com.bff.gaia.unified.sdk.options.PipelineOptions;

import com.bff.gaia.unified.sdk.transforms.windowing.BoundedWindow;

import com.bff.gaia.unified.sdk.values.PCollectionView;



/** <b><i>For internal use only; no backwards-compatibility guarantees.</i></b> */

@Internal

public class StateContexts {

  private static final StateContext<BoundedWindow> NULL_CONTEXT =

      new StateContext<BoundedWindow>() {

        @Override

        public PipelineOptions getPipelineOptions() {

          throw new IllegalArgumentException("cannot call getPipelineOptions() in a null context");

        }



        @Override

        public <T> T sideInput(PCollectionView<T> view) {

          throw new IllegalArgumentException("cannot call sideInput() in a null context");

        }



        @Override

        public BoundedWindow window() {

          throw new IllegalArgumentException("cannot call window() in a null context");

        }

      };



  /** Returns a fake {@link StateContext}. */

  @SuppressWarnings("unchecked")

  public static <W extends BoundedWindow> StateContext<W> nullContext() {

    return (StateContext<W>) NULL_CONTEXT;

  }



  public static <W extends BoundedWindow> StateContext<W> windowOnlyContext(W window) {

    return new WindowOnlyContext<>(window);

  }



  private static class WindowOnlyContext<W extends BoundedWindow> implements StateContext<W> {

    private final W window;



    private WindowOnlyContext(W window) {

      this.window = window;

    }



    @Override

    public PipelineOptions getPipelineOptions() {

      throw new IllegalArgumentException(

          "cannot call getPipelineOptions() in a window-only context");

    }



    @Override

    public <T> T sideInput(PCollectionView<T> view) {

      throw new IllegalArgumentException("cannot call sideInput() in a window-only context");

    }



    @Override

    public W window() {

      return window;

    }

  }

}